Model airplane variable-size pan



Feb. 27, 1962 w. E. HARTER MODEL AIRPLANE VARIABLE-SIZE PAN Filed April 17, 1959 United States Patent il 3,922,606 MODEL AIRPLANE VARIABLE-SIZE PAN Walter E. Harter, Belleville, lll., assigner to Harters Hobby Products, Inc., Belleville, Ill., a corporation of linois Filed Apr. 17, 1959, Ser. No. 867,225 4 Claims. (Cl. 46-76) This invention relates to model airplane construction, in general, and particularly involves a Speed pan for a model airplane.

The construction of model airplanes is a unique art within its held of items yfor the hobbyist, and yet there are a vast number of model airplanes available on the market. Although the model airplane may be designed for a number of user purposes, the construction of one type of model airplane is directed exclusively toward optimum conliguration for maximum speed. 'The hobbyist may lnd a number of uses and pleasures with the high speed model airplane, a common example being the well-known rat races, during which keenly competitive airplane runs are made by each competitor in an eifort to establish a maximum speed relative to the other contestants, and to the oilicial record which may have been set.

High speed model airplanes are available in a number of different sizes. One problem which the manufacturer of such air-planes encounters is the competitive necessity to provide for the purchasing public a full line of model airplanes ranging from the smallest to the largest, while yet producing such airplanes at the lowest possible manufacturing cost. The solution to such a problem becomes particularly important when the manufacturer has developed a model airplane design of unusually high speed characteristics. This invention is directed toward a speed pan lfor attachment to the fuselage of a model airplane. Ihe speed pan is so designed that it may be readily adapted [for use with any size model airplane. Therefore, it is an object of the present invention to provide such a speed pan.

Particularly, it is an object of the invention to provide a speed pan which is extremely light and which is designed for a minimum of air resistance.

A further, and a highly important, object of the invention is to provide a speed pan which has such design characteristics that one end of it may be cut olf according to the size of the airplane with which the speed pan is to be used. v

Another object of the invention is to provide a speed pan which can be adapted to diierent length model airplane fuselages using different length motor shafts, with or without a spinner.

Another object of the invention is to provide a speed pan which is extremely strong in construction while yet being light enough for use in a high speed model airplane.

Yet another object of the invention is to provide a speed pan for a model Yairplane fuselage which is extremely light in weight, but to which a landing gear, wings and motor may be attached.

Another object of the invention is the provision of a speed pan which may be die cast rather than sand cast, thereby eliminating the necessity of machining.

Other objects and advantages will become apparent from the description which is to follow.

In the drawings:

FIGURE l is a plan view of the speed pan;

lFIGURE. 2 is a 'view in section taken along the line 2 2 of FIGURE 1;

FIGURE 3 is an end view in elevation of the speed pan taken from the left of FIGURE 1;

HGURE 4 is a view in section taken along the line 4 4 of FIGURE l;

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FIGURE 5 is a view in section takenl along the line 5 5 of FIGURE l;

FIGURE 6 is a view in section taken along the line 6 6 of FIGURE 1;

FIGURE 7 is a view in section taken along the line 7 7 of FIGURE 1;

FIGURE 8 is a view in section taken along the line 8 8 of FIGURE 1;

FIGURE 9 is a view in section taken along the line 9 9 of FIGURE 1;

FIGURE 10 is a view in section taken along the line lil-10 of FIGURE 1;

FIGURE 1l is a view in section taken along the line Il ll of FIGURE l;

FIGURE 12 is a View in section taken along the line 1.2 12 of FIGURE l;

FIGURE 13 is a view in section taken along the line 13 13 of FIGURE 1;

FIGURE 14 is a view in section taken along the line III- 14 of FIGURE l;

FIGURE 15 is a view in section taken along the line 15-15 of FIGURE 1;

FIGURE 16 is a View in section taken along the line 16J-16 of FIGURE 1;

FIGURE 17 is a diagrammatic perspective view of a spinner-type model airplane incorporating the speed pan which is embodied by this invention; and

FIGURE 18 is a partial view of the forward end of the speed pan, showing a motor and propeller arrangement without a spinner.

The speed pan 2li is illustrated as being an elongated member. This speed pan 2i? is adapted to t onto the under section of a model airplane fuselage. (Such a model airplane is diagrammatically illustrated in FIG- URE 17.)

It can be seen from FIGURE 1 that the sides of the speed pan include opposite external forward surfaces 21 and 22 which originate at a forward end 23. The sides 21 and 22 define sweeping curves which converge toward one another at the forward end 23, and rearwardly thereof reach an area of maximum relative divergence (which may occur general-ly at the point Where the section 10 1) is taken). As the surfaces 21 and 22 extend further rearwardly, they again gradually converge up to about the point where the section 13 13 is taken. Thereafter, the surfaces 21 and 22 continue rearwardly in relatively long sections 24 and 2S, which are approximately straight, until the surfaces 21 and 22 nearly meet at the rear 26 of the speed pan. The rear 26 of the speed pan includes side and lower sections for ease of description. Thus,`

the lower surface 2S begins at the forward end 23 with a sweeping curve which becomes a generally straight line 29, terminating in the curved end 26.

The curvature of the external surface just described,

which begins at the forward ends 23 and terminates in the Vgenerally straight, elongated section (24, 25 and 29) is designed with the greatest considerationv of air resistance. That is to say,'with the external surface configuration of the speed pan illustrated, air resistance is a minimum. This configuration permits the application of the present speed pan to extremely high speed model air` into the fuselage interior.

radius of 18W/16 inches for the sweeping curve which begins `at the forward surface 23. The cross-sectional di'- ameter of the external surface at the forward end 23 may be 11%4VV inches. The internal diameter of the forward end 23 is-determined by the diameter of a propellerrsecuring washer.k In the embodiment illustrated, that internal dia-meter is 'V8 of an inch. (The association of the speed pan with a motor, propeller shaft and wash.- ers can be viewed a-t FGURE 18.)

In order to have as light a speed panas possible, it is desired to make the thickness as small as possible while yet preserving a very strong structure. i The shell lthickness of the forward section of the speed pan may be uniform for a short distance, for example,V the distance of 1%6 of an inch. This uniform thickness of the section 3() will, of course, require that the radiusof the internal surface at section 30 be gradually increasing rearwardly from the forward end 23. Y c

At the plane where the section S-S is taken on the speed pan, the radius of the internal surface sharply decreases. For example, at the plane where the. section 4 4 is taken, the radius of the internal surface 30 may be 6%4 of an inch, whereas at'the plane where the sec-V tion 5-5 is taken, the radius may be only V16 of an inch; The effect of this sharp change in Vthe interior surface of the speed pan is to present a bead 31 at the plane where the section 5--5 is taken. This bead 31 presents one plane at which the speed pan 2t) may be cut transverse to its axis lto adapt the speed pan to a model airplane smaller than one which might use the full length speedrpan 26. Y lo VThe presen-t speed pan may-be used with'a model airplane whichV may or may not have a spinner attached to Y (In competitive ilying, certain events permit the use of a spinner'whereas others, such as the rat'race, prohibit spinner models.) In either type it is an important, if not indispensable, feature that air ilow into the forward'interior of the fuselage be blocked off. For those models using a spinner, the air is automatically blocked olf by the spinner, inasmuch as the size of Va spinnerl'rnay 4be chosen to completely blanket the forward opening.A

For models 'which do not use a spinner, the size of the forward fuselage openingis/determined by the diameter of the propeller-securing washers,- One of those washers is xed to the propeller shaft and is of standard diameter, regardless of the length of the propeller shaft. Since the 'forward internal diameter' of the speed pan will be determined bythe diameter of the washer, the for- Ward internal diameter is established and must be maintained.' Therefore the bead 31, having an internal di- 'ameter which is the same as the'internal diameter of the forward end A23 (illustrated as being 7/8 of ran inch), willY cooperate withvthe propeller washer to block off-air ilow If the cut ismade immedialtely forward of the bead 31, the bead 31 willpreseut a surface of the proper diameter.

A second bead 33 is rearward of the beadv 31 and separated therefrom by a distance of of an inch, measured between the planes of minimum diameter. The second bead 33 will also have an internal diameter of:A 7s of an inch. Accordingly, the speed pan 20V `may have its forward fend cut o immediately forward of the second bead 33,Y and the second bead 33 would like-Y wise present an internal diameter of the correct size to cooperate with the propeller washer.Y c

' It should he noted that if a model airplane is to be used with a spinner, kthe speed pan may be cut at a bead 31` or 33 or'a't any other plane because the spinner applied will'eftectively blockthe ow of air into the fuselage. In fact, for spinner-type models, speed pansv of the type described may be cast without the beads. Such a speed pan will still incorporate the improved air ilow characteristics which are apart of this invention.l

Continuing rearwardly'along the .speed pan 20, a section 34 has thickened side walls, as. can be seen at FIG- ures 1, 8, 9 and 10. The relatively wide top surface of the speed pan, above the section 34, presents a strong surface and section to which the mounting lugs of a motor may be attached. Y(See FIGURE 18.)

The section 34 includes a raised, attened portion 3S on the bottom interior surface of the speed pan 2). The portion 35 may he approximately 11/2 inches long with a material thickness of a quarter inch at its maximum thickness. The portion 35 presents an area where a landing gear for the model airplane may be attached. The increased thickness of the portion 3S permits Ythe milling ofi of a at plane on the underV surfaceof the speed pan 20 adjacent the portion-35 towhich the landing gear might be attached.

Rearward of the portion 35 Vis a section 36 of reduced thickness for conserving weight. The section 36, which may be 11/2 inches long; is followed by a section 37 wherein the. sides ofthe speed pan have an increased thickness. The section 37 may be 1% inches in length and have a thickness of approximately Mt inch. It is to the top of the section 37 that the wings of thefmodel airplane maybe attached and, therefore, this section 37 is incrcasedrin thickness for added strength. The area 37 being longer than necessary to'attach the wing, flexibility inthe precise point of attachment is afforded. 'l'hus the wings may be attached to the section 37 anywhere between the forward end 38 and the rearward end 33 of the section 37. v

The relatively long extension 40 rearward of the section 37 has a very small thickness which may be Vonly %2 of an'inch. This extension 40 terminates short of the rear end26,V providing a solid section 41 between the section 46'Y andthe rear end 26. A stabilizer may be attached to the Vsection 41 and, since a rudder may be attached to tlierrfuse'lage above the section 41, it is desirable to provide the. increased lstrength alforded by Vforming the section 41 ofV solid construction.

`Altriough the section'40 is. very thin,V it is strong because offthejreinforcing skeleton-provided.VV This reinforcement includes a longitudinal-rearwardly tapering rib 42 beginning :at the forward edge 3S of thersection 37 therefrom to connect to theY andY extending rearwardly solid end section 41. Y Y

Depending from the longitudinal rib 42 are a plurality of transverse ribs 43, 44, 45 and 46, spaced as illustrated in-FIGURES 1 and V2. These transverse ribs in conjunction with the longitudinal rib'42, which are all formed with the die-casting, greatly add Vtothe strength Yof the present speed pan without materially increasing its weight. Arflattened, enlarged portion 47'is provided intermediate the ends of the long gitudinalVV rib;42.V The portion 47 'presents a surface to which the manufacturers trademark may be stamped.,l Y Y f A spinner-type model airplane is illustrated in FIGURE 17,;utilizing the speed pan-V20 of the present invention. Such anY airplane includes a fuselage 50, wings Si, a spin- 'ner 52, a propeller 53, a motor 54', a'landing gear 55, a

rudder 56 and a stabilizer 57. Y.A'propellershaft connecfing the propeller and spinner to the motor'isrnot visible. It'will be recognized from the exible y'design .of the present speed -pan that a plurality of different sized airplanes may employ Vthe speed panr20.

FIGURE 18 illustrates a motor assembly whichrdoes not incorporateV a spinner. This assembly vincludes the speed pan 20 (shown partially), and will include the beads 31 and 33. The motor 60 has mounting lugs 61 on either side of it. Holes 62 through these lugs permit the attachment of the lugs 61 to the upper surfaces of the section 34.Y The shaft 63 extending from the motor hasv a washer 64 fixed to it. A propeller 65 is secured to the shaft 63: between the washer 64 and another vwasher 66 Y by a nut 67 threaded onto the end of the shaft 63. The

Washer64 is located just forward of theV front end of the speed pan 20* and is of such a diameter that it extends 5 slightly beyond the internal edge of the pan, thus effectively blocking the flow of air into the interior. (The fuselage will tit onto the speed pan in the manner illustrated in FIGURE 17 with the washer 64 extending beyond its internal surface also.)

As illustrated in FIGURE 18, the shaft 63 is long enough that the Washer 64 is located at the front end 23 of the pan. However, it will be appreciated that for motors having shorter shafts, the pan will be cut, and the washer 64 will be positioned adjacent one of the beads 31 or 33. Y

One of the greatest costs in the construction of items of the type herein described is the labor cost. The present speed pan construction affords a tremendous saving in such cost. This is because the speed pan is die cast rather than sand cast for the unusual saving which will become apparent. It is true that the die is more expensive than is the cost of setting up the machinery for a sand casting. However, the present invention incorporates a unique structural arrangement permitting the use of a single die. The die produces a cast speed pan adaptable to a plurality of speed pan lengths merely by the cutting off of the forward section of the speed pan when it is to be used with a smaller aircraft. The die will be designed to cast the largest speed pan of a series, and that speed pan can be cut off for smaller applications.

lt is understood that the description heretofore presented, together with the accompanying drawings are intended to be illustrative only and that, while only a single embodiment has been shown and described, the invention is not to be so limited but is meant to be defined only by the scope of the claims which follow.

What is claimed is:

1. An attachment of the type described comprising a speed pan for fitting to the lower section of a model airplane fuselage, the pan having an open forward end for permitting the passage of a propeller shaft, the pan cooperating with the fuselage to enclose a section of the shaft, the pan having its interior cut out so as to define substantially a hollow shell, the thickness of which is variable along the length of the shell, the pan being of gradually increasing size over a portion of the distance from the forward end, as measured transversely of the axis of the speed pan, with the thickness of the pan wall being maintained substantially thin to maintain as much as possible a light weight pan, the interior of the pan having a head parallel to and spaced from the forward end, the size and shape of the innermost surface of the pan at a plane through the bead being the same as the size and shape of the internal surface at the forward end so that the pan may have its end forward of the bead cut off, and a second bead rearward of the first-mentioned bead, the size and shape of the innermost surface of the second bead being the same as that of the first bead, rendering the pan adaptable to a plurality of fuselage slzes.

2 The attachment of claim 1 wherein the pan is formed by die casting.

3. The speed pan of claim 1, wherein a thickened section is provided rearward of the forward end to permit the planar milling of the area underneath said section to facilitate the attachment of a landing gear thereto.

4. The speed pan of claim 1 including additional thickened sections to` facilitate the attachment of a motor carrying the propeller and the attachment of Wings to the pan.

References Cited in the rile of this patent UNITED STATES PATENTS 405,057 Taylor June l1, 1889 2,157,097 Jung May 9, 1939 2,238,702 McIntosh Apr. l5, 1941 2,555,670 Babcock lune 5, 1951 2,870,567 Bergstrand Ian. 27, 1959 

